| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide the communication terminal device equipped with a means which supplies electric power equivalent to paid charge to outside. SOLUTION: A public telephone set 1 and a portable information terminal 2 are connected by a power supply line 3 and a data communication line 4, and data are sent from the portable information terminal 2 to the public telephone set 1 through the data communication line 4. The public telephone set 1 sends the data to the telephone set of a communication partner. Further, electric power is supplied by the power supply line 3 from the public telephone set 1 to the portable information terminal 2. This electric power covers the operating electric power of the portable information terminal 2 and also charges the battery in the portable information terminal 2. The electricity charge used as communication charge is paid with a telephone card 5 similarly to an ordinary public telephone set 1. Consequently, the electric power equivalent to the paid charge is supplied from the public telephone set 1 to the portable telephone set 2, so even when the battery of the portable information terminal 2 is exhauted, communication can be made through the public telephone set 1. Further, the battery which is discharged can be charged.</p> |
